Is that green bin always the best solution?

Collect or grind?
In December 2014, the Waste Management Association published a piece entitled: “The green bin remains the best solution”. In this publication about the disposal of kitchen waste (GF waste), they highlight the advantages of the green bin (also referred to as bio bin). They oppose the alternative: the food waste disposer. When using a food waste disposer, the user takes care of the disposal of the kitchen waste himself and the collection service is no longer involved.

It is understandable that the members of the Waste Management Association do not want consumers to be able to make a different choice for the disposal of kitchen waste. The Association obviously has a commercial interest in not allowing the use of these grinders! Their publication is therefore quite tendentious; The advantages of the green bin are widely discussed and any negative points about the alternative, the grinder, are mainly emphasized. However, even they have to admit that using a grinder is very convenient for the consumer! Unfortunately, their publication contains incomplete and incorrect information, which gives a distorted representation of the facts.
Let's try to get a more realistic picture of this bio-bin versus grinder discussion:

Dispose of via the bio bin or via the grinder, both meet the condition of separation of household waste at the source. In both cases, the requirement that this must be done via regulated waste flows is also met. Only the method of transport and processing differs: solid waste from the bio bin is transported by truck and train to a composting plant and ground kitchen waste flows via the sewer to the WWTP for fermentation. So far the score is equal.

Using a bio bin to dispose of garden waste can be useful and kitchen waste can also be disposed of. But in the summer this becomes less attractive, because due to the high moisture content of kitchen waste, the vegetable and animal food remains begin to decompose quickly. Stench, flies, in short, unsanitary conditions. These lurk all year round for residents of high-rise buildings. It is therefore not surprising that in cities with many high-rise buildings, a large proportion of residents do not dispose of their GF waste separately. In a number of municipalities, GF waste is therefore no longer collected separately. So here the use of waste disposers in the kitchens would mean a significant environmental benefit!
Collection and transport of (G)FT waste is usually done by collection trucks running on diesel fuel. In their publication, the Waste Management Association ignores the emissions of extremely harmful particulate matter and of polycyclic hydrocarbons and carbon dioxide that this entails. The entire transport also costs a lot of energy. Disposing of ground kitchen waste through the sewer does not pollute the atmosphere at all and a grinder also uses very little energy (costs: approximately 10 euros per household per year).
Both the energy and the environmental balance are clearly in favor of the food waste disposer!

Abroad, especially in the United States, there is decades of experience with the use of food waste disposers. In the US, installing a grinder in the kitchens of new construction is often mandatory. That's not very expensive. In the Netherlands this could be done for around 100 euros per home in an apartment building. They last at least 10 years and are 100% recyclable. It can therefore easily withstand the comparison with the green container.

In their article, the Association states that discharge through the grinder causes all kinds of "valuable nutrients to flow into the sewer, while they themselves turn it into useful compost". An incorrect representation of the facts, because unlike garden waste, GF waste is not a valuable component for composting and the ground food waste is broken down in the digestion tanks in a WWTP. In addition to useful biogas (methane), this also produces heat.

The same objections are again and again raised against allowing food waste disposers in the kitchen. But what is the reality:
• The capacity of our sewage treatment system is not an obstacle. Calculations and practical research by TU Delft have shown that it would not pose any problem if 10% households started using a grinder. And achieving 10% penetration is expected to take decades.
• Damage to the sewer system due to possible acidification as a result of the use of grinders does not occur, as shown by extensive research abroad as well as calculations by TU Delft.
• The water consumption of a household will hardly increase (comparable to flushing the toilet one extra time). Don't forget that cleaning a biotank also uses water.
• Electricity consumption also increases only negligibly.
• Although the costs of sludge residue processing in the sewage treatment plant are increasing, this is largely or completely offset by the greater energy production during fermentation.
• Yes, a grinder represents an investment for the user, but not or hardly more than the purchase of a bio container.
• The total energy and environmental balance must also include the energy that the production and eventually the waste processing of the bin costs, plus the burden on the environment due to the collection of organic waste.
• Biodegradable waste is processed into compost. But compared to garden waste, GF waste is not a valuable fraction for compost preparation. It is better suited for fermentation in the liquid waste stream.

That things can also be done differently in the Netherlands is illustrated by the WaterSchoon project in a new district of Sneek. All homes there will have a food waste disposer in the kitchen. The sewage water is collected and purified locally. The energy this produces benefits the homes!

Summarizing:
• Allowing food waste disposers has major advantages, especially in high-rise buildings; it is more hygienic and will encourage a greater percentage of GF waste to be disposed of separately.
• There are hardly any disadvantages:
– No problems are expected for the existing sewer system.
– The current sewage treatment plants (RWTP) can handle the consequences without any problems, especially with a penetration rate of food waste grinders below 10% of households.
– From an environmental point of view, the balance is positive compared to current practice.

Conclusions regarding the use of food grinders:

• This method of separated GF disposal deserves a full place in our waste processing system.